Currently the FireSplitter control can only have 2 child forms next to each other or below each other.
But you can nest FireSplitter controls as my demo shows.
It is not exactly the same as one FireSplitter having 3 child forms in a row, (because you move 2 splitter bars at the same time) but it comes close.
The demo also shows how you can fetch the splitter bar position (and set it).
Kind regards
Cool! Happy to hear that the splitter control is working okay for you. Nice solution you've come up with to have three vertical or horizontal splitters.